How to predict drive number change for 7.3->8.1 upgrade?

Marat N.Afanasyev amarat at
Fri Sep 17 13:04:35 UTC 2010

Michael Sperber wrote:
> Oliver Fromme<olli at>  writes:
>> Michael Sperber<sperber at>  wrote:
>>   >  I just upgraded my desktop system from 7.3 to 8.1, and the main hard
>>   >  drive, which was /dev/ad6 before is now /dev/ad10.  Consequently, the
>>   >  initial boot failed when trying to mount the root file system from ad6.
>>   >
>>   >  The desktop system is now fixed, but I also have a rented server with
>>   >  only a serial console, and I worry that the upgrade is going to leave me
>>   >  with a dead machine.  Is there any way to predict how the drive number
>>   >  changes?  (Why does it change at all?)  If so, what's the proper way to
>>   >  tell the system the initial root device *before* rebooting?
>> Remove "options ATA_STATIC_ID" from your kernel config
>> before building the new kernel and rebooting.  Then your
>> first disk will be ad0, no matter what controller and
>> channel it is connected to.  Be sure to update your
>> /etc/fstab file.
> Ah, excellent - that's what I was looking for.  Thanks!
beware of drago^Wchanging of adX numbers each time you add/remove drive 
;) It's better to label filesystems, imho ;)

SY, Marat

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